Fixed Frequency Air Condition Implementation Using SPMC65P2408A

Abstract:This document mainly introduces the design of the main control board of fixed frequency air condition. The board, taking sunplus 8-bit SPMC65P2408A MCU as the core, features four-channel AD to detect temperature, AC220V current and power-down; two-channel external interrupt to detect the indoor fan speed and zero-crossing point; capture function to receive infrared codeWith its high performance and reasonable resources, SPMC65P2408A is particularly suitable for application in home appliance such as air condition, washing machine etc.
Keyword: Air Condition, Sunplus MCU, SPMC65P2408A

1 Introduction
In recent years, air condition industry has been growing rapidly in China. In the year 2000, the number of domestic air conditions has reached around 18 million. In 2003, the total throughput in air condition industry outnumbered 40 million, which rose to 55 million in 2004Presently, the domestic output accounts for 3/5 of the world's total amount. China has been playing a leading role in air condition manufacture as well as being in the course of becoming the manufacturing base for world's air condition. Both production value and sales income have increased year by year in the past five years, and changes in 2001, 2003 and 2004 are extremely remarkable.
Besides, in recent years, more and more families begin to use air conditions. But the total amount possessed differs in different areasAs the expansion of domestic market, the air condition export keeps increasing year after year, which is the same with the export proportion in home applianceIn 2002, 2003 and 2004, the export kept a strong increasing tendency, thereinto the export volume outnumbered 140 billion in 2003 for the first timeIn 2004, it had outnumbered 230 billion, going steadily with the domestic sales volume.
This document aims to popularize the application of SPMC65family MCU and test the performance according to nation standard.

1 The Working Principle of Air Condition
(1) Refrigeration Principle

Figure 1.1 Refrigeration Principle

The refrigeration principle is shown in Figure 1.1. When the air condition is running, low-pressure and low temperature refrigerant steam in the refrigeration system is compressed to the high pressure, high temperature stream by a compressor and outputted to the condenser. At one time, the outdoor air being absorbed in the condenser takes away the heat generated by the refrigerant.

Therefore, the high pressure, high temperature refrigerant steam is turned to the high pressure liquid. Through throttle capillary, high pressure liquid is turned to low pressure and low temperature liquid and outputted to the evaporator for evaporating under the low pressure and absorbing heat; at one time, the indoor fan makes the indoor air into the evaporator constantly to exchange heat and sends cold air to the room.

Therefore, the indoor and outdoor air circulates constantly to cold down the room temperature.

(2) Heat Principle

Figure 1.2 Heat Principle

The air condition heat pump can warm up the room by the condensation heat that generated by the refrigerating system, shown in Figure 1.2. In the evaporator, the low pressure, low temperature refrigerant liquid can evaporate and absorb heat; in the condenser, the high-temperature, high-pressure refrigerant gas sends out heat and is condensed to liquid.

When heat pump is working, it changes the current circulation direction of refrigerant by a four way valve to make the indoor coil pipe turn from a refrigerating evaporator into a heat evaporator. Therefore, refrigerating system can absorb heat outdoor and send out heat indoor to warm the room.

2 Function
Refrigeration Mode
1) Range of temperature: 16℃～30℃, default: 24℃;
2) Frost proof.
Dehumidify Mode
Under the dehumidify mode, the indoor temperature is set in a range of 16℃～30℃ by the remote controller. The processor gets the working mode according to the difference between the indoor temperature and the set temperature
Heat Mode
1) Range of the temperature: 16℃～30℃;
2) Cold air prevention under the heat mode;
3) Defrosting;
4) High Temperature protection.
Blowing Mode
Under the blowing mode, only the indoor fan operates and the speed can be switched among high, middle and lowThe set temperature is ignored.
Timing On/Off
You can set the time of timing on/off with a minimum unit of 10 minutes. Once meeting the set time, the machine will begin to run or stop running.
Air Flap Operation
1) You can decide the air flap to be in the continuous mode or the fixed mode;
2) In refrigeration, dehumidifying, blowing and automatic run modes, the flap swings between 150° and
105°;
3) In heat mode, the flap swin